客語和其他漢語相同，動詞後面可以跟隨修飾動詞的補語，如果在動詞跟補語之間插入其他詞組，則該動詞必須被複製於介入詞組與補語之間。本文以優選理論分析上述動詞重疊結構，並主張由於補語必須緊貼動詞，這個動詞強制重疊現象可以經由兩個規範詞素位置的制約條件來解釋。另一方面，如果補語緊跟在動詞之後，該動詞不能接受複製，此現象可由「強制性非等值原則」來說明，此原則不允許相同成分相鄰，如果動詞複製會造成兩個相同動詞相鄰，便違反此一
強制原則。

This paper investigates the obligatory syntactic process in Hakka called “verb reduplication”, of which a verb is reduplicated when followed by a CP headed by the clitic do. By providing an OT-based analysis, this paper argues that the syntactic operation is triggered by two ABUT constraints. When a verb takes a do-phrase to further describe its denoted action, if there exists another constituent in-between the verb and its following CP, attaching do to either the verb or the intervening constituent violates one of the ABUT. Hence, the verb must be reduplicated to create a structure that fulfills the requirement of both constraints. Contrastively, if the do-phrase immediately follows the verb, attaching do to its preceding main verb does not violate any of the ABUT. Here, the disallowance of verb reduplication can be captured by the Obligatory Contour Principle (OCP), which functions as a crucial syntactic condition to block reduplication, knowing that its occurrence would cause the adjacency of two identical verbs.